A passive optical network (PON) is a system for providing network access over “the last mile.” In a downstream direction, the PON may be a point-to-multi-point (P2MP) network comprising an optical line terminal (OLT) at a central office, an optical distribution network (ODN), and a plurality of optical network units (ONUs) at customer premises. Ethernet passive optical network (EPON) is a PON standard developed by the Institute of Electrical and Electronics Engineers (IEEE) and specified in IEEE 802.3ah, which is incorporated herein by reference as if reproduced in its entirety. EPON may provide a simple and flexible way of using optical fiber for broadband service in the last mile.
In EPON, an optical fiber may be used for both upstream and downstream transmissions with different wavelengths. The optical line terminal (OLT) may implement an EPON media access control (MAC) layer for transmission of Ethernet frames. A multi-point control protocol (MPCP) may perform various services such as bandwidth assignment, bandwidth polling, auto-discovery, and ranging. Ethernet frames may be broadcasted downstream based on a logical link identifier (LLID) embedded in a preamble of each frame. On the other hand, upstream bandwidth may be assigned based on the exchange of Gate and Report messages between messages between an OLT and an ONU.
Recently, hybrid access networks employing both EPON and other network types have attracted growing attention. For example, Ethernet over Coax (EoC) may be a generic name used to describe all technologies that transmit Ethernet frames over a unified optical-coaxial (coax) network. Examples of EoC technologies may include EPON over coax (EPoC), data over cable service interface specification (DOCSIS), multimedia over coax alliance (MoCA), G.hn (a common name for a home network technology family of standards developed under the International Telecommunication Union (ITU) and promoted by the HomeGrid Forum), home phoneline networking alliance (HPNA), and home plug audio/visual (A/V). EoC technologies may have been adapted to run outdoor coax access from an ONU to an EoC head end with connected customer premises equipment (CPEs) located in subscriber homes.
There is a rising demand to use EPON as an access system to interconnect with multiple coax cables to terminate coax network units (CNUs) located in a subscriber's home with an EPoC architecture. In an EPoC system, as a physical (PHY) layer in the optical network portion may be relatively cleaner than a physical layer in the coax network portion, one may need to establish channel communication between CNUs and OLT before transmission of data. Some traditional discovery and registration approaches may use EPON MPCP for registration of coaxial line terminals (CLTs). However, traditional MPCP may not be used for the coax network portion. Thus, it is desirable to extend the EPON MPCP to the coax portion of an EPoC network, where noises may be higher.